Table 3.
Distribution of categories of heat-related illness cases, by query type (NSSP BioSense “heat, excessive” and CSTE novel heat-related illness) and period (full year, heat season, and cooler season), Maricopa County, Arizona, January 1 to December 31, 2015
| Case Classification by Query Type | No. (%) | ||
|---|---|---|---|
| Full Year (Jan 1 to Dec 31) | Heat Season (May 1 to Sep 30) | Cooler Season (Jan 1 to Apr 30; Oct 1 to Dec 31) | |
| BioSense “heat, excessive” query | 791 (100.0) | 647 (100.0) | 144 (100.0) |
| Probable heat-related illness case | 589 (74.4a) | 547 (84.5a) | 42 (29.2a) |
| ICD-9-CM or ICD-10-CM diagnosis code (992, E900, T67, or X30)b | 388 (49.1) | 363 (56.1) | 25 (17.4) |
| Chief complaint text (natural heat exposure) | 201 (25.4) | 184 (28.4) | 17 (11.8) |
| Undetermined heat-related illness case | 16 (2.0) | 11 (1.7) | 5 (3.5) |
| Ruled-out heat-related illness case | 186 (23.5) | 89 (13.8) | 97 (67.4) |
| Novel heat-related illness query | 674 (100.0) | 594 (100.0) | 80 (100.0) |
| Probable heat-related illness case | 591 (87.7a) | 547 (92.1a) | 44 (55.0a) |
| ICD-9-CM or ICD-10-CM diagnosis code (992, E900, T67, or X30)b | 354 (52.2) | 328 (55.2) | 26 (32.5) |
| Chief complaint text (natural heat exposure) | 237 (35.2) | 219 (36.9) | 18 (22.5) |
| Undetermined heat-related illness case | 21 (3.1) | 14 (2.4) | 7 (8.8) |
| Ruled-out heat-related illness case | 62 (9.2) | 33 (5.6) | 29 (36.3) |
Abbreviations: CSTE, Council of State and Territorial Epidemiologists; ICD-9-CM, International Classification of Diseases, Ninth Revision, Clinical Modification; ICD-10-CM, International Classification of Diseases, Tenth Revision, Clinical Modification; NSSP, National Syndromic Surveillance Program.
aPositive predictive value = total number of probable heat-related illness cases / total number of records identified by the query as possible heat-related illness cases.
bCodes to include: 992, effects of heat and light; E900, accident caused by excessive heat; T67, effects of heat and light; X30, exposure to excessive natural heat.